Which process model notation is primarily used for describing information systems requirements?

The Unified Modeling Language (UML) is specifically designed for modeling software and information systems. It provides a standardized way to visualize the design of a system through various diagrams, which make it easier to capture both functional and non-functional requirements. UML is widely utilized in software development for requirement specification, including class diagrams, use case diagrams, and sequence diagrams, which collectively help stakeholders understand system interactions, data flows, and relationships among components.

In contrast, the other notations serve different purposes. Flow charts are primarily used for detailing the steps in a process but lack the depth needed for complex information system requirements. Event-driven process chains (EPC) are useful for modeling business processes and workflows but are less effective at representing the detailed interactions and structures of software systems. Value Stream Mapping (VSM) focuses on identifying and analyzing the flow of materials and information in processes, primarily in lean management contexts, rather than on requirements specification for information systems. Hence, UML stands out as the most suitable notation among the choices for describing information systems requirements.